It depends on what sound you're inputting. For the recording I did below I had it listening directly to iTunes rather than listening to the mac book pro's onboard mic. If you're VJing and can get a direct audio input from the dj (if possible). If not then I guess the next best would be a cardiod directional (shotgun) mic pointed at a speaker. But I guess what ever you do you don't want to slow down the rate that it hears the music in order to keep sync.
Good luck.
Disclaimer: I'm not an audio person but a video allrounder, there could be better solutions out there

Eavan